A Bailey DV26 will do the job perfect.
Baileys make the nicest dump noise from my experience but they dont tend to last that long, also from my experience.
http://cgi.ebay.co.uk/FIAT-PUNTO-UNO-GT-TURBO-IE-TWIN-PISTON-DUMP-VALVE-KIT_W0QQitemZ150169698105QQihZ005QQcategoryZ10382QQssPageNameZWDVWQQrdZ1QQcmdZViewItem looks like mine, does'nt say what make? Ant!
UTs do need a twin piston one to work........ir so they should
mines a freek UT and runs a diaphrame dump valve and its mega loud! unlike the bailey ones and forge ones which sound a little tisssssssssssss, mine makes a great big foook offf PERRRRTISHHHHHHHHHHHHHHH noise. really deep and loud, not tinney and wimp like the twin piston ones sound IMO.
you'l only need a replacement manifold inlet pipe, for reverting back, and dont chuck the recirc valve! Ant!
look on puntosports, theres a used bailey DV recirc type (I think) going for 35notes posted
I was tempted, but my bodywork is more serious matter than fancy engine stuff.